HP TGT Non-Medical aur Commission Exams mein Physics ka weightage kafi zyada hota hai. Motion (Gati) chapter physics ki neeve (foundation) hai. Aksar students simple definitions padh lete hain par Graphs aur Numericals mein phans jate hain.
Aaj hum Motion chapter ko basic se lekar Exam Level tak cover karenge. Isme hum Scalar/Vector, Equations of Motion, aur Circular Motion ke key points samjhenge.
1. Fundamental Quantities (Mool Rashi)
Motion samajhne se pehle Scalar aur Vector ka fark samajhna zaroori hai.
| Quantity | Definition | Example |
| Scalar (Adish) | Sirf Magnitude (Matra) hoti hai, Direction nahi. | Distance, Speed, Mass, Time. |
| Vector (Sadish) | Magnitude + Direction dono hote hain. | Displacement, Velocity, Acceleration, Force. |
2. Distance vs Displacement (Doori vs Visthapan)
Exam mein yahan se conceptual sawal aate hain.
Distance (Doori): Raste ki kul lambai. Yeh kabhi zero nahi ho sakti.
Displacement (Visthapan): Initial aur Final point ke beech ki Shortest Distance.
Note: Displacement Zero ho sakti hai (Agar aap ghoom kar wapas wahin aa gaye).
Example: Ek circle (radius $r$) ka ek poora chakkar lagane par:
Distance = $2\pi r$
Displacement = $0$
3. Speed & Velocity (Chaal aur Veg)
Speed: Rate of change of distance. (Scalar)
Velocity: Rate of change of displacement. (Vector)
Average Speed Formula:
$$Average Speed = \frac{\text{Total Distance}}{\text{Total Time}}$$(Yeh formula numericals ke liye most important hai).
4. Acceleration (tvaran)
Definition: Rate of change of velocity.
Retardation (Mandan): Jab velocity ghat rahi ho (Negative Acceleration), toh use Retardation kehte hain.
Unit: $m/s^2$
5. Graphical Representation (Graphs) - Most Important for TGT
Graphs se sawal pakka aata hai. Inhe rat lo:
A. Displacement-Time Graph (s-t Graph)
Agar graph straight line hai: Uniform Velocity.
Slope (Dhalan): Is graph ka slope Velocity deta hai.
B. Velocity-Time Graph (v-t Graph)
Agar graph straight line hai: Uniform Acceleration.
Slope: Is graph ka slope Acceleration deta hai.
Area: Graph ke niche ka area Displacement (Doori) batata hai.
6. Equations of Motion (Gati ke Sameekaran)
Yeh tabhi lagte hain jab Acceleration Constant ho.
- $$v = u + at$$
- $$s = ut + \frac{1}{2}at^2$$
- $$v^2 - u^2 = 2as$$
Where: $u$ = Initial velocity, $v$ = Final velocity, $a$ = Acceleration, $s$ = Distance, $t$ = Time.
7. Circular Motion (Vrittiye Gati)
Jab koi object circle mein ghoomta hai:
Speed: Constant reh sakti hai.
Velocity: Har point par badalti hai (kyunki direction change hoti hai).
Centripetal Acceleration: Center ki taraf lagne wala acceleration.
Formula:
$$a = \frac{v^2}{r}$$
8. HP TGT Special MCQs (Practice Set)
Q1. An athlete completes one round of a circular track of diameter 200m in 40s. What will be the displacement at the end of 2 minutes 20 seconds?
A) 0 m
B) 200 m
C) 2200 m
D) 100 m
Ans: B (Hint: Total time = 140s. Rounds = 3.5. So, he is at the opposite end. Displacement = Diameter).
Q2. The slope of a velocity-time graph gives:
A) Distance
B) Displacement
C) Acceleration
D) Speed
Ans: C
Q3. A car goes from A to B at 40 km/h and returns from B to A at 60 km/h. What is the average speed?
A) 50 km/h
B) 48 km/h
C) 0 km/h
D) 240 km/h
Ans: B (Formula: $\frac{2xy}{x+y} = \frac{2 \times 40 \times 60}{100} = 48$).
Q4. If a body starts from rest, what is the ratio of distance covered in 1st second, 2nd second, and 3rd second?
A) 1:2:3
B) 1:4:9
C) 1:3:5
D) 1:1:1
Ans: C (Galileo’s Law of Odd Numbers).
Q5. The numerical ratio of displacement to distance is always:
A) Less than 1
B) Equal to 1
C) Equal to or less than 1
D) Greater than 1
Ans: C
Quick Revision Formulas Table
| Concept | Formula / Fact |
| Average Speed | $\frac{2v_1v_2}{v_1+v_2}$ (for equal distance) |
| Equation 2 | $s = ut + \frac{1}{2}at^2$ |
| Equation 3 | $v^2 = u^2 + 2as$ |
| Circular Acc. | $a = \frac{v^2}{r}$ |
| Slope of x-t | Velocity |
| Area of v-t | Displacement |
9. Motion Under Gravity (Gurutva ke Adheen Gati)
Equations of Motion tab badal jati hain jab koi object upar phenka jaye ya niche gire. Yahan acceleration $a$ ki jagah gravity ($g$) le leti hai.
Value of $g$: $9.8 m/s^2$ (Numericals mein kabhi-kabhi $10 m/s^2$ lete hain).
Sign Convention (Chinh Paripati):
Numericals solve karte waqt yeh galti mat karna:
Downward Motion (Niche aana): $g = +ve$, Velocity badhti hai.
Upward Motion (Upar jana): $g = -ve$, Velocity ghat-ti hai.
Highest Point: Upar jakar highest point par Final Velocity ($v$) = 0 hoti hai.
Modified Equations:
$v = u + gt$ (Downward) / $v = u - gt$ (Upward)
$h = ut + \frac{1}{2}gt^2$ (Height $h$ ban jati hai)
$v^2 = u^2 + 2gh$
10. Distance Traveled in $n^{th}$ Second
Yeh concept TGT Exams ka favorite hai.
Agar pucha jaye ki "5 seconds mein kitni doori tay ki", toh formula $s = ut + \frac{1}{2}at^2$ lagega.
Lekin agar pucha jaye ki "Sirf 5vein (5th) second mein kitni doori tay ki", toh alag formula lagega:
Where: $n$ = woh specific second (jaise 5th, 6th).
Example:
Ek car rest ($u=0$) se start hoti hai aur acceleration $2 m/s^2$ hai. 3rd second mein kitni doori chalegi?
$S_{3rd} = 0 + \frac{2}{2}(2 \times 3 - 1)$
$S_{3rd} = 1(6 - 1) = 5$ meters.
11. Relative Velocity (Sapeksh Veg) - Conceptual
Jab do cheezein move kar rahi hon, toh unki speed ek doosre ke hisab se kya hai?
Same Direction (Samaan Disha):
Agar Car A (60 km/h) aur Car B (40 km/h) same direction mein ja rahi hain, toh A ki speed B ke mukable:
$$V_{rel} = V_A - V_B = 60 - 40 = 20 \text{ km/h}$$Opposite Direction (Vipreet Disha):
Agar wo ek doosre ki taraf aa rahi hain (Accident scenario):
$$V_{rel} = V_A + V_B = 60 + 40 = 100 \text{ km/h}$$(Yahi wajah hai ki head-on collision zyada khatarnak hota hai).
12. Angular Variables in Circular Motion
Circular motion mein hum meter/second nahi, balki Angle/second dekhte hain.
A. Angular Displacement ($\theta$):
Kitna angle ghooma. Unit: Radian.
B. Angular Velocity ($\omega$ - Omega):
Angle change hone ki raftaar.
Relation between Linear ($v$) and Angular velocity ($\omega$):
13. Advanced Numericals (Mains Level)
TGT Commission mein numericals thode tricky aate hain. Inhein samjhein:
Problem 1 (Gravity):
A ball is thrown vertically upwards with a velocity of $20 m/s$. How high will it go? ($g=10 m/s^2$)
Solution:
$u = 20 m/s$, $v = 0$ (at top), $a = -10$ (upward).
Formula: $v^2 - u^2 = 2ah$
$0^2 - (20)^2 = 2(-10)h$
$-400 = -20h$
$h = 20$ meters.
Problem 2 (Graphs):
The velocity-time graph of a body is parallel to the time axis. What does it imply?
Answer: Iska matlab velocity change nahi ho rahi hai (Constant Velocity). Acceleration Zero hai.
Conclusion
Physics mein Motion chapter sirf formulas ratne ka naam nahi hai, balki concepts ko apply karne ka hai. TGT exam mein Graphs aur Average Speed ke sawal sabse zyada galat hote hain, isliye unpar focus karein.
Next Chapter:
Agli post mein hum "Force and Laws of Motion" (Newton ke Niyam) aur "Momentum Conservation" padhenge. Stay Tuned!
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